1. Field of the Invention
The present invention relates to a magnet type heater which is used for promoting starting performance of an engine mainly for various kinds of vehicles such as an automobile with a power source of a diesel engine or a gasoline engine particularly in cold time or extremely cold time and as auxiliary heating means of a fluid in a pipe such as cooling water of an engine used for various kinds of vehicles including an electric automobile or for heating a cabin in a ship, which is used for preheating or rapid temperature elevation (shortening of warming up time) of cooling water for a generator driven by an engine and an engine of a welder, a compressor or a construction machine and which can be utilized for temperature elevation of a catalyst apparatus of emission gas of an engine or fuel gas for a fuel cell.
2. Description of the Prior Arts
There has been known a viscous type heater as a heat source of auxiliary heating for a vehicle such as an automobile which is utilized in heating cooling water of an engine in starting operation in a cold district (refer to JP-A-2-246823, JP-A-4-11716U, JP-A-9-254637, JP-A-9-66729, JP-A-9-323530 or the like).
A viscous type heater is of a type in which viscous fluid such as silicone oil is made to generate heat by shearing, the generated heat is exchanged by circulating water circulating in a water jacket and used as a heat source for heating. As a structure thereof, for example, a heat generating chamber is formed in a housing, a water jacket is formed at an outer region of the heat generating chamber, a drive shaft is rotatably supported by the housing via a bearing apparatus, a rotor rotatable in the heat generating chamber is fixed to the drive shaft, a viscous fluid such as silicone oil is enclosed in a gap between a wall face of the heat generating chamber and the rotor, circulating water is taken into the water jacket from a water intake port and is circulated to deliver from a water delivery port to an outside heating circuit.
According to the viscous type heater integrated to a heating apparatus of a vehicle, when the drive shaft is driven by an engine, the rotor is rotated in the heat generating chamber and accordingly, the viscous fluid generates heat at the gap between the wall face of the heat generating chamber and an outer face of the rotor by shearing, the generated heat is exchanged by the circulating water in the water jacket and the heated circulating water is used for heating the vehicle as cooling water of the engine.
Further, as a method of purifying to reduce NOx in emission gas of an engine, there is a method of heating the emission gas by heating a catalyst installed in a pipe by an electric heater (EHC) arranged to be proximate to the catalyst.
The viscous type heater is featured in that downsizing and cost reduction can be realized by a simple structure, high reliability and safety can be ensured by a noncontact type mechanism having no wear and when water temperature is elevated and an auxiliary heater is dispensed with, the operation is automatically stopped by temperature control and accordingly, wasteful energy is not used. However, according to silicone oil used as a viscous fluid, the viscosity is gradually reduced and the shear resistance is reduced with an increase in the rotational number of the rotor and accordingly, temperature attained by heat generation of silicone oil is limited to about 240.degree. C. and accordingly, there is a difficulty in which temperature of the circulating water cannot be elevated so high, some time period is required until the silicone oil is agitated in starting operation and accordingly, rapid heating effect cannot be achieved when the engine is cold. Accordingly, in the case of a cold district specified vehicle mounted with a diesel engine, such a viscous type heater cannot be regarded as sufficient in view of the effectiveness and there has been desired an auxiliary heater capable of heating a fluid in a pipe to high temperature in a shorter period of time and more efficiently.
Further, according to the method in which the catalyst is heated and activated by the electric heater (EHC), there is a difficulty in which some time is required in elevating the catalyst to a catalyst activation temperature, for example, in the case of a diesel engine, emission gas temperature is lowered by high function formation, and particularly, in idling, the catalyst temperature becomes as low as 100.degree. C. and the purification capability of the NOx catalyst cannot sufficiently be achieved.